Crankshaft butchers.

[Tomas]

rather than making a pin from scratch, if this engine has been fitted with a later rod, which has a larger big end, could you use the matching pin for that rod and machine out the crankshaft halves to suit that ?   
 {assuming there is enough space/clearance  to do this}
or make a stepped pin out of the later type pin ?   
at least it would be the correct material and the bearing area wouldn't need machining
just a thought { I am usually wrong on this sort of subject}

Machining the crank wheels is the way I normaly do it if the original is no longer available and there are others available that match the lenght but with bigger pins. The owner of the crank in this case managed to find a NOS rod which has been fitted.
The stepped pin option is OK if made properly but each time a new rod kit is needed a new stepped pin is needed as well but with machined out wheels the new kit goes straight in.

Was the NOS rod RM 125B rod?  RM 125B pins and big end bearing should still be available? Not sure why would some one made stepped pin for this application.

[Daryl Jones]

I'd forgive a back yarder for this type of work but it didn't come from one.

As a backyarder, I couldn't even forgive myself, for that kind of work. 

Cheers, Daryl.

[sleepy]

rather than making a pin from scratch, if this engine has been fitted with a later rod, which has a larger big end, could you use the matching pin for that rod and machine out the crankshaft halves to suit that ?   
 {assuming there is enough space/clearance  to do this}
or make a stepped pin out of the later type pin ?   
at least it would be the correct material and the bearing area wouldn't need machining
just a thought { I am usually wrong on this sort of subject}

I think it is an RM125B. I haven't tried Suzuki to check stocks but they could have been in a big hurry to get it going.
I recently converted a set of RM125B wheels to take the latter rod but it was done that way to recover wheels that had be badly broached. I could have sleeved the wheels but that would have been more costly. Also the later rod with bigger pin and nice silver platted cage is a more robust unit. The stock RM bearing when used in road race can't handle the extra RPM that is needed to be competitive.

Machining the crank wheels is the way I normaly do it if the original is no longer available and there are others available that match the lenght but with bigger pins. The owner of the crank in this case managed to find a NOS rod which has been fitted.
The stepped pin option is OK if made properly but each time a new rod kit is needed a new stepped pin is needed as well but with machined out wheels the new kit goes straight in.

Was the NOS rod RM 125B rod?  RM 125B pins and big end bearing should still be available? Not sure why would some one made stepped pin for this application.

[sleepy]

I'd forgive a back yarder for this type of work but it didn't come from one.

As a backyarder, I couldn't even forgive myself, for that kind of work. 

Cheers, Daryl.

Yes Daryl but as a backyarder your engineering knowlege is better than most.
They say that a good engineer is not one that knows everything but knows how to find the correct information.

[Momus]

8620 is another suitable case hardening steel.

[sleepy]

8620 is another suitable case hardening steel.

I'll stick with the EN36 it has a better core strenght and fatigue resistance according to the specs. My theory is you are going to the trouble to make a part use the best material available and know it will work.

[Lozza]

8620 is another suitable case hardening steel.

All crankpins and gears are made from EN36 .....for a very good reason they harden very well but stay ductile under the hardening. No gear cutter will use anything else.

[Mick D]

I would be wanting the correct material used, if and when the time comes for the dearest option to replace a no longer available Transmission gear with a one off make?

All steel alloy manufactures who produce EN36 say it is not for transmission gears, because it has a chromium content.
All steel alloy manufacturers of EN series under the British Standard BS970 recommend EN34 as the correct stock for transmission gears(Zero Chromium).

Yet you say

All gears are made from EN36 ...... No gear cutter will use anything else.

Can you show me some documentation or a valid link to one manufacturer of alloy steel that says otherwise than what I have stated? Just one?

In the absence of proof? Can you tell us which "gear cutters" are ignoring the manufacturers of EN36 instructions and advise, so we can avoid them please. 

[Lozza]

I would be wanting the correct material used, if and when the time comes for the dearest option to replace a no longer available Transmission gear with a one off make?

All steel alloy manufactures who produce EN36 say it is not for transmission gears, because it has a chromium content.
All steel alloy manufacturers of EN series under the British Standard BS970 recommend EN34 as the correct stock for transmission gears(Zero Chromium).

Yet you say

All gears are made from EN36 ...... No gear cutter will use anything else.

Can you show me some documentation or a valid link to one manufacturer of alloy steel that says otherwise than what I have stated? Just one?

In the absence of proof? Can you tell us which "gear cutters" are ignoring the manufacturers of EN36 instructions and advise, so we can avoid them please.

Albins Modena and Coljen all use EN36.Feel free to ask. All the gear I've had Col make are made from EN36. Pretty sure Ellis Moore in the UK uses EN36.

[Mick D]

Yes sure EN36 is a great choice for vintage Crank pins, but it is not the only available choice, by far.

This

All crankpins are made from EN36 ....

is just simply Not True.
 
EN36 is only one choice of several different but still suitable offerings from different manufacturers.

It is just not a matter of "Standards" either. 
JIS SCH420H varies slightly in content, performance and working requirements to EN36 as does alloy made to the American Society standard of ATSM-4115

All slightly different.
Sometimes it is
 Bang for buck, adequate performance, built to a price.
Or
 Superior performance, built to a higher price.

For example,
Hot rods use ATSM-4115 for Crank-pins
http://www.hotrodsproducts.com/productinfo.aspx?cat_details_id=34

Royal Rods use SCH420H for their Crank-pins
http://www.con-rod.com.tw/products.htm

There are other Crank-pin manufacturers who don't use EN36 either, so these facts are a along way from

EN36 A/B is the only material to make it from.

All crankpins are made from EN36 ....

 
 

[Mick D]

Albins Modena and Coljen all use EN36.Feel free to ask. All the gear I've had Col make are made from EN36. Pretty sure Ellis Moore in the UK uses EN36.

I don't know who these people are lozza, and maybe sadly, but I don't care either.
Maybe they should submit their CV's to all of these Steel Alloy producers and tell them how wrong they are doing it?

In the UK hey? Ok,
Well in that case I will go with one of the UK companies, say "Yorkshire Steel"
Here is the link, they all tell the same story
http://www.westyorkssteel.com/alloy-steel/case-hardening-steel/en34/

And in all fairness I used that link because there is also the goodies there on EN36

As I basically said, "if I were going through that expense for a gear? I would want the most durable outcome and the correct one.

And as I also said and still think it is a great path to tread when required

I have a piece of EN36A sitting here waiting to be turned into oversize pins. The plan is to machine up a batch of 24 and 25mm pins that are .5mm oversize, get them case hardened and then grind to suit honed out rods for hard to get stuff. It's a good way to bring back cranks that are worn but only if they haven't had an overheat. Just got to get the time to do it and decide what to make them for.

That's a great time saving alternative for blokes like me in those difficult to get rod situations Sleepy.
I am not quite set up to do it.
So the next one that is difficult to find, but existing is savable, you will be hearing from me

[sleepy]

I'd have to agree with Mick that there are a number of different steels would do the job for a bigend pin. Localy here is Brisbane we don't to many choices but can get EN36A.
As for gears a number of years ago I had some gears made for a speedway car that I built the engine for. The motor was a turbocharged and supercharged GS750 with reduced bore to 700cc. It was making upto 240hp at the tyres although not often raced at that boost level for traction reasons.
The gears replaced 2nd gear and were about 1.75 times as thick. The first batch were made out of EN36A and case hardened to .020" giving HRC 58. They lasted quite well but still failed by breaking teeth( out lasted stock 10 times).
A 2nd batch was made this time by myself and I used E110 and case hardened to .030" with HRC 60 , they were also cryo treated and shot penned and they are still in the engine but it has not been used for a few years now. A set went into a GS1000 speedway engine as well and I have 1 set still here if anyone want them.

[OverTheHill]

without yet reading it all i may as well get shot down in flames lol. Ran a VW king pin as a big end pin in my Mk8 Pursang which was a couple of thou bigger after i'd had the original out & in too many times & just wasn't tight enough to be safe. What was 'that' VW pin made of?. Wonder who bought it after i'd finished with it--bad man 'me'. Loved that bike & raced it from new. Just kept fixing it--if ya call that fixing it. Might've got two pins out of one king pin but too long ago to remember. Can remember going around town with a micrometer annoying everyone with stupid questions. Then i got an MX250B.

[Lozza]

Albins Modena and Coljen all use EN36.Feel free to ask. All the gear I've had Col make are made from EN36. Pretty sure Ellis Moore in the UK uses EN36.

I don't know who these people are lozza, and maybe sadly, but I don't care either.
Maybe they should submit their CV's to all of these Steel Alloy producers and tell them how wrong they are doing it?

In the UK hey? Ok,
Well in that case I will go with one of the UK companies, say "Yorkshire Steel"
Here is the link, they all tell the same story
http://www.westyorkssteel.com/alloy-steel/case-hardening-steel/en34/

And in all fairness I used that link because there is also the goodies there on EN36

As I basically said, "if I were going through that expense for a gear? I would want the most durable outcome and the correct one.

And as I also said and still think it is a great path to tread when required

I have a piece of EN36A sitting here waiting to be turned into oversize pins. The plan is to machine up a batch of 24 and 25mm pins that are .5mm oversize, get them case hardened and then grind to suit honed out rods for hard to get stuff. It's a good way to bring back cranks that are worn but only if they haven't had an overheat. Just got to get the time to do it and decide what to make them for.

That's a great time saving alternative for blokes like me in those difficult to get rod situations Sleepy.
I am not quite set up to do it.
So the next one that is difficult to find, but existing is savable, you will be hearing from me

Albins have made gear sets for just about every rally car that finished a stage in Australia and make the gear sets for the Nissan V8 supercar.

Modena more for you high end Ferarri's and such. Modena made a very trick ICC kart gearbox that allows flat shifting up and down the gearbox without electronic intervention

Coljen for motorcycles and superkarts in Australia.

Ellis Moore makes 90%of the gear sets for classic bikes in the UK.

EN36 no good for crank pins, better go onto Kiwibiker forum and explain that to Wayne "Wobbly" Wright(ex GP engineer/BSL 500 designer) he has it all wrong and shouldn't have made all those crank pins from EN36

how would they get it all wrong at the same time?


 

[Mick D]

EN36 no good for crank pins, better go onto Kiwibiker forum and explain that to Wayne "Wobbly" Wright(ex GP engineer/BSL 500 designer) he has it all wrong and shouldn't have made all those crank pins from EN36

Never once at any time did I say EN36 is no good for Crankpins, Did I? Well?
Lets keep this simple as to avoid more of your misstruths.

I said EN36 is not the only choice of material for crank pins and no doubt you are well aware of exactly that, all knowing of everything!

So show us where I said EN36 is no good for crankpis, without lying this time.